<html>
<head>
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/semantic-ui/2.2.4/semantic.min.css">
<!--  <link rel="stylesheet" type="text/css" href="semantic/dist/semantic.min.css"> -->
</head>
<body>
<body>
    <div class="ui sidebar inverted vertical menu">
      <a class="item">1</a>
      <a class="item">2</a>
      <a class="item">3</a>
    </div>
    <div class="pusher">
      Site content
    </div>
</body>
  <script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
  <script src="https://cdn.jsdelivr.net/semantic-ui/2.2.4/semantic.min.js"></script>
  <script>
$('.ui.sidebar')
.sidebar('toggle')
; 
  </script>
<!--  <script src="semantic/dist/semantic.min.js"></script> -->
</body>
</html>